Dear EarthTalk: Several tragic accidents recently brought to light the lethal dangers of mines to mine workers. What are the environmental issues with mining, including their long-term impact on both public and mine workers" health?

—Ed Kelley, Albuquerque, NM

Mining is an inherently nasty practice when looked at from either environmental or health standpoints. For starters, large-scale excavation, which disrupts topsoil and displaces wild flora and fauna, is often needed to get at relatively small amounts of ore. And the leftover waste or "runoff" often contains toxins like mercury and sodium cyanide that can contaminate local water sources. The smelting that processes the ore can cause sulfurous dust clouds that lead to acid rain. And to add insult to injury, abandoned mines are often later used as unregulated landfills for hazardous wastes.

Examples of environmental mining disasters abound. One of the most well known happened in Martin County, Kentucky in 2000, where 250 million gallons of toxic chemical- and metal-containing liquid waste burst through a coal waste dam. That accident killed 1.6 million fish and contaminated drinking water for 27,000 people. Jack Spadaro, who oversees area enforcement for the U.S. Mine Safety and Health Administration (MSHA), didn"t put local residents at ease when he told reporters at the time that 200 other locations in the region could do the same at any moment.

The West Virginia-based Coal River Mountain Watch works to prevent disasters of such magnitude by lobbying lawmakers to pass reforms, urging enforcement officials to increase their vigilance and educating the public about the risks in their own backyards. The non-profit group focuses its efforts primarily on "mountaintop removal" mining operations, which blast off the tops of mountain peaks to get at underlying coal deposits. The vegetation and forest loss that results from such operations increases flooding and landslides, and the waste byproducts poison local water sources.

In the United States, Congress has tried to clean up the mining industry through passage of the Surface Mining and Reclamation Act of 1977 and then the Superfund law in 1986 (requiring cleanup of toxic sites, including mines, after they have been abandoned), but enforcement of these laws has been spotty at best.

Mining remains fundamentally dangerous to mine workers as well, separate from the risks of accidental death. Mine workers are often exposed to unhealthy levels of irritants such as asbestos, uranium and even diesel exhaust from heavy machinery. Emphysema and cardiovascular problems are common among miners, and cancer rates are higher than average as well.

Despite highly publicized episodes like the tragic explosion at the Sago mine in West Virginia this past January, MSHA claims that mining has gotten safer for workers in recent years. While 22 workers lost their lives as a result of accidents at mines in the U.S. last year, they say, that figure represents a 50 percent reduction from a decade earlier. Nonetheless, the specter of death looms large over the mining industry, and many workers are scurrying to find jobs in other fields.

Dear EarthTalk: What killed all the birds and other sea life last summer on the U.S. west coast?

—Nate McKenzie, Bothell, WA

Scientists remain puzzled over what caused such widespread loss of wildlife last summer on the Pacific coast between Northern California and British Columbia. Researchers estimate that more than 100,000 dead seabirds washed ashore, and that as many as 40 percent of the young salmon that normally inhabit the region"s coastal waters that time of year were absent. Meanwhile, other researchers recorded massive die-offs of zooplankton, a keystone of the marine food chain, off the coast of Oregon.

While scientists were perplexed, wildlife watchers were just plain depressed. Some reported seeing birds starve to death on their favorite ocean beaches, while others counted abandoned nests instead of thriving seabird colonies. Beach surveys in May in California found dead birds with emaciated bodies, atrophied muscles and empty stomachs. In Washington, cormorants, normally found dead only occasionally (every 34 miles of beach) were found in substantially larger numbers averaging one every eight-tenths of a mile, according to the Coastal Observation and Seabird Survey Team at the University of Washington. There were also reports of sightings of "emaciated grey whales."

What scientists do know is that cool winds deviated from their normal northerly course in May, and ocean water temperatures rose two to seven degrees above normal during June. This in turn flushed the nutrients normally available near the ocean surface far below, depriving marine wildlife of the all-you-can-eat buffet they have come to expect during the late spring and early summer.

Whether or not the two scenarios were related is unclear, but some say that global warming is an important factor. Quoted in the Seattle Times, Bill Peterson, an oceanographer with the National Oceanic and Atmospheric Administration (NOAA) in Newport, Oregon, said, "People have to realize that things are connected—the state of coastal temperatures and plankton populations are connected to larger issues like Pacific salmon populations."

Nate Mantua, a research scientist with University of Washington"s Climate Impacts Group, says that the odd combination of weather conditions in the summer of 2005 would have to repeat themselves frequently over the next two decades to "lend more weight to the notion that something has changed in coastal climate and that it may be linked to global warming." That weight may already be building: According to Science Daily, 2005 was already the third consecutive year in which above average ocean temperatures have occurred.

John McGowan of the Scripps Institution of Oceanography in La Jolla, Calif., told the Seattle Post-Intelligencer: "It’s all the way up and down the coast. … There’s a lot of evidence there are important changes going on in the Pacific coast system." Whatever the cause, scientists are eager to see if such a scenario repeats itself in coming years, and will have their monitoring equipment ready and well tuned.